This invention relates to a vacuum operated device, particularly to a vacuum operated device suitable to be used for ignition timing adjustment of an internal combustion engine as its exhaust gas purifying measures.
In a conventional internal engine, particularly in one for automobiles, during the time of low temperature if a throttle valve of a carburetor is opened by a little combustion of the fuel-air mixture is not effected enough, thereby increasing components of HC and CO in the exhaust gas. In order to decrease these components, it is necessary to advance ignition timing. On the other hand, during the time of low temperature if the throttle valve is opened large, knocking is brought about. In such a case, the ignition timing must not be advanced.
Thus, it is necessary to control the ignition timing also according to various throttle valve openings.